Internally damped circuit articles

Abstract

The present invention provides a method of improving the vibrational damping characteristics of a circuit article. The method involves adding damping layer(s) to the laminate material that is processed into a circuit article. The damping material effectively increases the damping of the circuit article and reduces the amplitude of resonant frequencies of the circuit article excited by environmental vibrations or shocks that the circuit board may encounter in use and thereby potentially improving the performance of the circuit article for vibration and shock related performance issues without the addition of add-on dampers to the circuit articles surface or by isolating the circuit board by means of vibration and shock isolators.

What is claimed is: 
     
       1. An internally damped circuit article comprising: (a) a circuit article laminate structure; and   (b) vibration damping material, wherein the vibration damping material is incorporated into the circuit article laminate structure.   
     
     
       2. The circuit article of claim 1 containing at least one vibration damping layer comprising a reinforcement fiber material at least partially coated or impregnated with a vibration damping material. 
     
     
       3. A circuit article containing at least one layer of a vibration damping material comprising a viscoelastic material, said vibration damping material having a loss factor of at least about 0.01 and a storage modulus of at least about 6.9×10 3  Pascals. 
     
     
       4. The circuit article of claim 1 selected from the group consisting of circuit boards and flexible circuits. 
     
     
       5. The circuit article of claim 1 selected from the group consisting of circuit boards. 
     
     
       6. The circuit article of claim 1 wherein the vibration damping material is placed in the circuit article where one or more vibrational modes are active. 
     
     
       7. The circuit article of claim 3 wherein said vibration damping material has a loss factor greater than about 0.1 and a loss modulus of at least about 6.9 ×10 4  Pascals. 
     
     
       8. The circuit article of claim 3 wherein said vibration damping material has a loss factor of about 0.5 to about 10 and a storage modulus of about 6.9×10 4  to about 1.4×10 7  Pascals. 
     
     
       9. The circuit article of claim 3 wherein said circuit article contains at least two layers of vibration damping material. 
     
     
       10. The circuit article of claim 3 wherein the vibration damping material layer(s) each has a thickness of about 0.005 to about 0.51 mm. 
     
     
       11. The circuit article of claim 3 wherein the vibration damping material layer(s) each has a thickness of about 0.013 to 0.13 mm. 
     
     
       12. The circuit article of claim 3 wherein the viscoelastic material is selected from the group consisting of thermoset polymers, thermoplastic polymers, and blends thereof. 
     
     
       13. The circuit article of claim 3 wherein the vibration damping material further comprises a fibrous material. 
     
     
       14. The circuit article of claim 3 wherein the vibration damping material includes an amount of fibrous material effective to improve vibrational damping of the circuit article by a factor of about 2. 
     
     
       15. The circuit article of claim 13 wherein the vibration damping material includes about 3 to about 60 weight percent fibrous material, based on the total weight of the vibration damping material. 
     
     
       16. The circuit article of claim 15 wherein the fibrous material is nonmetallic fibrous material. 
     
     
       17. The circuit article of claim 16 wherein the nonmetallic fibrous material is glass. 
     
     
       18. The circuit article of claim 3 wherein the vibration damping material further comprises a particulate material. 
     
     
       19. The circuit article of claim 3 wherein the vibration damping material includes an amount of particulate material effective to improve vibration damping of the circuit article by a factor of about 2. 
     
     
       20. The circuit article of claim 3 wherein the vibration damping material includes about 0.5 to about 70 weight percent of particulate material based on the total weight of the vibration damping material. 
     
     
       21. The circuit article of claim 18 wherein the particulate material is selected from the group consisting of glass bubbles, glass beads, ceramic bubbles, ceramic beads, thermally conductive bubbles, aluminum oxide powder, aluminum nitride powder, silica, and cured epoxy nodules. 
     
     
       22. The circuit article of claim 3 wherein the vibration damping material further comprises a fibrous material and a particulate material. 
     
     
       23. The circuit article of claim 22 wherein the vibration damping material includes about 0.5 to about 70 weight percent total of fibrous material plus particulate material based on the total weight of the vibration damping material. 
     
     
       24. The circuit article of claim 3 wherein the vibration damping is improved by at least about 10% in at least one vibrational mode. 
     
     
       25. The article of claim 3 which contains a single layer of vibration damping material wherein said layer is positioned within the article at a distance of at least about 5% of the thickness of the article from an upper and lower surface of the article. 
     
     
       26. The article of claim 3 which contains a single layer of vibration damping material wherein said layer is positioned within the article at a distance of at least about 30% of the thickness of the article from an upper and lower surface of the article. 
     
     
       27. The circuit article of claim 3 wherein the circuit article has one layer of damping material positioned equidistant from an upper surface of the article and a lower surface of the article. 
     
     
       28. The article of claim 3 which contains at least two layers of vibration damping material wherein each damping material layer is positioned within the article such that it is at least about 5% of the thickness of the article away from an upper and lower surface of the article and each vibration damping material layer is at least about 5% of the thickness of the article away from another vibration damping layer. 
     
     
       29. The article of claim 3 which contains at least two layers of vibration damping material wherein each damping material layer is positioned within the article such that it is at least about 5% of the thickness of the article away from an upper and lower surface of the article and each vibration damping material is at least about 20% of the article thickness away from another damping layer. 
     
     
       30. The article of claim 28 which contains at least two layers of vibration damping material wherein each damping material layer is positioned within the article such that it is at least about 5% of the thickness of the article away from an upper and lower surface of the article and each vibration damping material is at least about 30% of the article thickness away from another damping layer. 
     
     
       31. The circuit article of claim 3 wherein the vibration damping material further comprises an electrically conducting particle material that conducts in only one direction. 
     
     
       32. The circuit article of claim 3 wherein the vibration damping material further comprises an epoxy resin material, wherein said epoxy resin material may optionally have vibration damping properties. 
     
     
       33. The circuit article of claim 3 wherein the vibration damping layer is a continuous layer. 
     
     
       34. The circuit article of claim 3 wherein the vibration damping layer is a continuous layer made up of adjacent sections of different vibration damping materials having optimal damping properties over different temperature ranges. 
     
     
       35. The circuit article of claim 3 wherein the article contains at least two layers of vibration damping material, wherein at least two of the layers comprise different damping materials having optimal damping properties over different temperature ranges. 
     
     
       36. The circuit article of claim 3 wherein the vibration damping layer is a discontinuous layer. 
     
     
       37. The article of claim 36 wherein the discontinuous layer comprises sections of damping material separated by non-damping material or spaces.